Optimization of growth condition of Barvar2 plant growth promoting Bacteria

Phosphorus (P) is one of the most important and essential elements for plant growth and development. Insufficient phosphorus in the soil has high effect on the plant growth and productivity. Chemical Pi fertilizer is used to provide the phosphorus for the plants which in the soil environment is mostly fixed into insoluble form and become unavailable to the plants. Using biofertilizers containing Pi solubilising bacteria (PSB) hydrolyses P from various phosphate compounds resulting in decreasing application of the chemical Pi fertilizers. Proper and economical production of biofertilizers is depend on the mass production of microorganisms formed the biofertilizer which is obtained by suitable culture medium and fermentation process. In the previous project, two Pi solubilising bacteria named P5 and P13 were isolated from soil samples collected from various regions of Iran and characterized. The application of these bacteria as biofertilizer was investigated. In the present project, various culture media for growth and proliferation of the bacteria (Pseudomonas putida strain P13 and Pantoea agglomerans strain P5) were investigated. The results showed that the bacteria could grow in the complex and semi-defined media properly. The Taguchi statistical method was used for design and optimization of the culture medium. The results of the optimization in the flask and fermentor indicated that the P5 could grow on the semi-defined medium to high cell density up to optical density (OD600) of 25 (17.5 g cell dry wt l-1) and P13 grew in the complex medium and reached to OD600=18.6 (14.5 g cell dry wt l-1) in short cultivation time of 8.5 hours. Growth of two different bacteria forming biofertilizer into high cell density with the same time is important and valuable regarding industrial production of biofertilizer